Defect in fatty acid oxidation: laboratory and pathologic findings in a patient.

The clinical, laboratory, and pathologic findings in a patient with a previously undescribed deficiency in fatty acid oxidation are summarized. The patient had a fatal defect in fatty acid metabolism profoundly affecting heart, skeletal muscle, liver, and kidney. Oxidation of palmitate was 38-51% of controls. Complementation assays demonstrated that the patient's fibroblasts complemented fibroblast lines from all known defects in fatty acid oxidation except long-chain acyl-CoA dehydrogenase deficiency. Urine and serum carnitine profiles also were indicative of a defect in the oxidation of long-chain substrate; however, the palmitoyl-CoA dehydrogenase activity was actually increased. This finding indicates that the patient had a defect that was distinct from, but possibly related to, long-chain acyl-CoA dehydrogenase deficiency. This patient demonstrates the laboratory and pathologic findings in defects in fatty acid oxidation and how they differ from those in Reye syndrome.